Google is experimenting with the open-source version of Sun's Solaris operating system as a possible long-term prelude to replacing its massive global network of Linux servers, according to sources.

With dozens of data centers worldwide estimated to house hundreds of thousands of Intel servers supporting its flagship search engine, a Google move to OpenSolaris would be another of several recent votes of confidence for the platform.

Propelled by the release of Solaris' source code 15 months ago as well as new Advanced Micro Devices-based servers from Sun that run it, the nearly 2-decade-old operating system is experiencing something of a midlife resurgence. More than 5 million users have registered to use Solaris 10 since its release in January 2005, a figure that includes those paying Sun for support and those using it for free.

Google officials declined to comment. According to Sun and other sources, a number of other companies are using Solaris 10 or Solaris Express, the executable version of OpenSolaris, which technically only refers to the Solaris source code and the community around it. That list of companies includes eBay, which touts its use of Solaris 10 on its home page; Yahoo, Vonage, Wal-Mart.com, Bear, Stearns & Co., Disney Mobile, and Reuters Group.

"Google, eBay, Yahoo -- pick your favorite," said Sun CIO Robert Worrall, whose internal IT team runs Solaris Express throughout Sun and has advised many customers on its deployment. Worrall confirmed that Google already runs a "significant amount" of Solaris in its data centers and is one of a number of customers "excited about the possibility" of moving more Linux servers to AMD Opteron servers from Sun running some version of Solaris.

Google runs a stripped-down version of Red Hat Linux specially modified by its engineers. But another source, a Solaris systems administrator who recently interviewed for a job at Google, said he was told the company plans to create and test its own modified version of OpenSolaris.

"I am 100% certain that there are literally dozens of people horsing around with OpenSolaris inside Google," said Stephen Arnold, a technology consultant and author of The Google Legacy. Moving to OpenSolaris, he said, would be a natural move for Google, with its large number of former Sun employees and its never-ending drive to push the performance of its data centers to the hilt. But Arnold said he doubts that Google, which finished rolling out its highly-secret data centers in 2004, is deploying OpenSolaris widely yet. "Will it quickly replace Linux anytime soon? No," he said.

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